CARB toroidal roller bearings – a revolutionary...

CARB® toroidal roller bearings – a revolutionary concept

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Contents

1 Product information.................................................. 3The winning combination............................................. 3SKF toroidal roller bearings with revolutionary design characteristics.................................................. 4

SKF Explorer class bearings ....................................... 5The range for all requirements .................................... 6

Availability.................................................................... 7Bearing features and benefits ..................................... 7

The CARB toroidal roller bearing – the cornerstone of the new self-aligning system...... 8Successful in service ................................................... 10

2 Recommendations....................................................12Selection of bearing size ............................................ 12

Longer life or downsizing ............................................ 12Design of bearing arrangements ............................... 14

Radial location ............................................................ 14 Axial location .............................................................. 16Design of adjacent components ................................ 18Sealing the bearing arrangement ................................ 20

Lubrication ................................................................... 22Grease lubrication ...................................................... 22Deviating conditions ................................................... 24Oil lubrication .............................................................. 25

Mounting ...................................................................... 26Mounting on cylindrical seatings................................. 26Mounting on tapered seatings..................................... 27

Dismounting ................................................................. 34Dismounting from a cylindrical seating ....................... 34Dismounting from a tapered seating ........................... 35

SKF concept for cost saving ....................................... 36

3 Product data ..............................................................37Bearing data – general ................................................ 37Product tables .............................................................. 44

CARB toroidal roller bearings ..................................... 44Sealed CARB toroidal roller bearings.......................... 56CARB toroidal roller bearings on adapter sleeve ........ 58CARB toroidal roller bearings on withdrawal sleeve ... 68

Other associated SKF products ................................. 78

SKF – The knowledge engineering company ............ 82

The SKF brand now stands for more than ever before, and means more to you as a valued customer.

While SKF maintains its leadership as the hallmark of quality bearings throughout the world, new dimensions in technical advances, product support and services have evolved SKF into a truly solutions-oriented supplier,creating greater value for customers.

These solutions encompass ways to bring greater productivity to customers, not only with breakthrough application-specific products, but also through leading-edge design simulation tools and consultancy services,plant asset efficiency maintenance programs, and theindustry’s most advanced supply management techniques.

The SKF brand still stands for the very best in rolling bearings, but it now stands for much more.

SKF – The knowledge engineering company

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The winning combination

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Self-alignment ...Self-aligning bearings are the hallmarkof SKF – not surprising since SKF wasfounded in 1907, based on the inventionof the self-aligning ball bearing by SvenWingquist. But the development didnot stop there, other SKF inventionsfollowed: the spherical roller bearing in1919 and the spherical roller thrustbearing in 1939.

Self-alignment is called for where

• misalignment exists as a result ofmanufacturing or mounting, or

• shaft deflection under load occurs

and these have to be compensated forin the bearing arrangement withoutnegative effects on performance orany reduction in bearing service life.

... and axial displacement ...SKF was also heavily involved in thedevelopment of bearings having ringsthat can be axially displaced withrespect to each other. In 1908, forexample, the cylindrical roller bearingin its modern version was largelydeveloped by Dr.-Ing. Josef Kirner ofthe Norma Compagnie in Stuttgart-BadCannstatt, which became a subsidiaryof AB SKF.

Cylindrical roller bearings are ap-plied when

• heavy radial loads and relativelyhigh speeds prevail and

• thermal changes in shaft lengthmust be accommodated in the bear-ing with as little friction as possible –provided, of course, that there is noimportant misalignment.

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... combined for successPreviously, it was always necessary tocompromise. Because misalignment orshaft bending makes the use of self-aligning bearings essential – and,depending on load and speed, thechoice lay between self-aligning ballbearings and spherical roller bearings.

However, in contrast to cylindricalroller bearings, those bearings cannotaccommodate important axial dis-placements within the bearing.

Therefore, it was necessary for one of the bearings to move axially in itshousing seating. Such movement isalways accompanied by considerablefriction, which produces internal axialforces in the bearing arrangement. Theresult is a shortened bearing servicelife and relatively high costs for main-tenance and repairs.

Today, this is a thing of the past.Because Magnus Kellström, a productdesigner at SKF, had a brilliant idea; he invented the toroidal roller bearing.This bearing not only can compensatefor misalignment without friction, butalso for changes in shaft length withinthe bearing. Thus a completely newtype of bearing for non-locatingarrangements has become available to the engineering world.

It is no longer necessary to com-promise, and there are added benefitstoo – much longer service life for thecomplete bearing arrangement andminimized maintenance and repaircosts.

Self-alignment …

… and axial displaceability …

… combined in a toroidal rollerbearing

1 Product information 2 Recommendations 3 Product dataThe winning combination Page ............... 12 Page ............... 37

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The toroidal roller bearing is a com-pletely new type of roller bearing, whichoffers benefits that were previouslyunthinkable. Irrespective of whether anew machine is to be designed or anolder machine maintained there arebenefits to be gained. Which of thesecan be exploited depends on themachine design and requirements.

The SKF toroidal roller bearing rep-resents one of the most importantbreakthroughs in rolling bearing tech-nology over the past sixty years. Thebearing was presented on the marketin 1995 under the SKF trademarkCARB®.

The bearing is a single row rollerbearing with relatively long, slightlycrowned rollers. The inner and outerring raceways are correspondinglyconcave and symmetrical (➔ fig ).The outer ring raceway geometry isbased on a torus (➔ fig ), hence theterm toroidal roller bearing.

The SKF toroidal roller bearing isdesigned as a non-locating bearingand combines the advantages of

• the self-aligning ability of the spher-ical roller bearing, and

• the ability of the cylindrical and needle roller bearings to accommo-date axial displacement within thebearing.

Additionally, if required, the toroidalroller bearing can be made as com-pact as a needle roller bearing.

An application incorporating an SKFtoroidal roller bearing provides bene-fits outlined in the following.

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Self-aligning capabilityThe self-aligning capability is a pre-requisite if misalignment arising fromfabrication or mounting, or shaft bending resulting from the use of longshafts or as a consequence of the load,have to be compensated for (➔ fig ).Angular misalignment of up to 0,5°between the bearing rings can beaccommodated without any detrimen-tal effects on the bearing or on servicelife. This means that the bearing cancope with the errors of alignment andshaft bending normally encountered inoperation.

Axial displaceabilityPreviously the only bearings that couldcompensate for thermal changes inshaft length were cylindrical and needle roller bearings. Now there isthe toroidal roller bearing (➔ fig ).The inner ring can be displaced withrespect to the outer ring by up to 10 %of the bearing width. By installing thebearing so that one ring is initially dis-placed with respect to the other one, it is possible to extend the permissibleaxial displacement in one direction. Incontrast to cylindrical and needle rollerbearings that require accurate shaftalignment, this is not needed for toroidalroller bearings, which can also copewith shaft deflection under load. Thisprovides a solution to many problemcases.

Long system lifeSelf-alignment combined with friction-less accommodation of axial displace-ment within the bearing implies bene-fits for the complete bearing arrange-ment (➔ fig ). 5

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The CARB toroidalroller bearing

SKF toroidal roller bearings with revolutionary design characteristics

1Fig

2Fig

3Fig

4Fig

5Fig

The torus

Angular misalignmentThe most frequentlyoccurring misalign-ments in operationare not a problemfor the CARBtoroidal roller bearing

Axial displacement Changes in shaftlength are accom-modated within thebearing virtuallywithout friction

FreedomPermissible angularmisalignment + axialdisplacement withinthe bearing

1 Product information 2 Recommendations 3 Product dataCustomer benefits Page............... 12 Page................ 37

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1• Internal additional forces resulting

from friction due to axial displace-ment do not occur, thus the operat-ing conditions are considerablyimproved.

• It is only the external loads thathave to be supported by the non-locating bearing as well as thelocating bearing.

• The bearings run cooler, the lubri-cant lasts longer and maintenanceintervals can be appreciably extended.

Taken together, these benefits con-tribute to a longer system life.

High load carrying capacityThe load carrying capacity of CARBtoroidal roller bearings is very high. In fact, the cross section is optimallyused, incorporating very long rollers ofmaximal diameter. A large number ofrollers makes them the strongest of allaligning roller bearings. They can copewith small deformations and seatingmachining errors (➔ fig ). These arecompensated for by the bearing ringsand there is no danger of edge stress-es being produced. High load carryingcapacity combined with this robust-ness provides opportunities toincrease productivity and machineuptime.

6

6Fig

7Fig

8Fig

Increased performance or downsizingFor non-locating bearing arrangementsincorporating a CARB toroidal rollerbearing, there are no induced internalaxial forces. Together with high loadcarrying capacity this means that

• for the same bearing size in thearrangement, performance can beincreased or the service life extend-ed, or

• new machine designs can be mademore compact to provide the same,or even higher performance.

Reduced vibrationNon-locating bearing arrangementswith CARB toroidal roller bearings arestiff. The CARB bearing must be radial-ly and axialy located in the housing aswell as on the shaft, since any thermalchanges in shaft length are accommod-ated within the bearing. Self-aligningball or spherical roller bearings in con-vertional non-locating bearingarrangements need to have a slidingpossibility, e.g between the bearingouter ring and housing seating. Thisresults in high axial vibrations causedby friction in the sliding movement.This problem is eliminated in non-locating bearing arrangements incorp-orating a CARB toroidal roller bearing,axial vibrations are therefore reducedto a minimum (➔ fig ).

Full dimensional interchangeabilityThe boundary dimensions of SKFCARB toroidal roller bearings are inaccordance with ISO 15:1998. Thisassures full dimensional interchange-ability with self-aligning ball bearings,cylindrical roller and spherical roller bearings in the same Dimension Series.The CARB bearing range also coverswide bearings with the low cross sec-tions normally associated with needleroller bearings (➔ fig ).

SKF Explorer classbearingsAll CARB bearings are manufactured tothe SKF Explorer performance class.

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Deviations fromcylindrical form areless problematicDemands on accur-acy of form of thebearing seatings are less stringent,making simpler andless costly arrange-ments possible

Axial vibrationWith a CARB bearing the axial vibration isconsiderably reduced, meaning longer service life and quieter operation

Full interchangeabilityNon-locating conventional self-aligning as well as rigid bearing arrangements can berefurbished with CARB bearings to gain the benefits

1 Product information 2 Recommendations 3 Product dataCustomer benefits Page............... 12 Page................ 37

time

axial vibration

– conventional arrangement– with CARB as non-locating bearing

The range for all requirements

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The SKFstandard range of CARB toroid-al roller bearings comprises bearings in13 ISO Dimension Series (➔ fig ). Thesmallest bearing has a bore diameter of25 mm and the largest one a bore dia-meter of 1250 mm. Bearings with a borediameter up to 1800 mm can be pro-duced. Whether a new bearing arrange-ment is to be designed or an existingarrangement upgraded most often thereis an appropriate CARB toroidal rollerbearing available or such a bearing couldbe manufactured to replace a non-locat-ing self-aligning ball bearing, or a spher-ical, cylindrical or even a needle rollerbearing.

SKF toroidal roller bearings are pro-duced in

• a caged version (➔ fig ) as well as• a full complement version (➔ fig )

with

• a cylindrical bore, or • a tapered bore.

The tapered bore has a taper of 1:12or 1:30, depending on the DimensionSeries.

32

1

C 39 C 49 C 59 C 69 C 30 C 40 C 50 C 60 C 31 C 41 C 22 C 32 C 23

1Fig

Overview of product range

1 Product information 2 Recommendations 3 Product dataAssortment Page ............... 12 Page ............... 37

In addition to the standard bearings,SKF also produces special executionsto suit particular applications, e.g.

• bearings with case hardened innerrings to allow a heavy interferencefit on the shaft/journal of dryer orYankee cylinders, for example;

• bearings with a surface hardenedcage for vibrating screens;

• sealed bearings, for example, forcontinuous casting plants (➔ fig ).The permissible misalignment andaxial displacement as well as theload carrying capacity are lowerthan for the corresponding bearingwithout seals.

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1

AvailabilityThe product range is shown in theproduct tables from page 44 onwards.Bearings listed without a triangle areavailable from stock or at short notice.It is advisable to check the availabilityof bearings marked with a triangle.Please contact SKF or your nearestdistributor. The standard range isbeing continuously extended and theintention is to manufacture all theproducts shown in the product tablesin a few years time.

Bearing features and benefitsAlready well-proven in service, the useof toroidal roller bearings enablesmachines, equipment and even plantsto be made

• smaller,• lighter,• more cost favourable,• more operationally reliable, and• with longer service life.

The replacement of other non-locatingbearings by CARB equivalents pro-vides increased performance anduptime. Why not put them to the testand reap the benefits as a machinebuilder or user.

3Fig 4Fig

Sealed bearingLubricated for life and protected against contamination

Full complement bearingFor very heavy loads and low speeds

2Fig

Caged bearingFor heavy loads and relatively high speeds

1 Product information 2 Recommendations 3 Product dataAssortment Page ............... 12 Page ............... 37

1 Product information 2 Recommendations 3 Product dataSelf-aligning bearing system Page ............... 12 Page ............... 37

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The CARB toroidal roller bearing– the cornerstone of the newself-aligning bearing systemThe conventional solutionUntil recently a self-aligning bearingsystem consisted of two self-aligningball bearings if loads were light andspeeds high, or two spherical rollerbearings when the loads were heavyand speeds more moderate. Thesebearing systems are simple, have goodload carrying capacity and can com-pensate for misalignment resulting frommanufacture or mounting errors, as wellas shaft deflection under load (➔ fig ).So far, so good – but what happens ifthermal changes in shaft length occur?

If the changes are to be accommo-dated it is necessary for one of thebearing rings to be able to move axial-ly relative to its seating; generally thismovement takes place between theouter ring and the housing seating.This is possible if the outer ring has a loose fit in the housing, which is notalways without problems and may justify the need for a compromise.

Any accommodation of lengthchanges between a bearing and itsseating is always accompanied by friction, which not only gives rise toinduced internal axial forces in thebearing (➔ fig ) but also axial vibra-tions. This is because the axial move-ment is not smooth, but of the stick-slip type (➔ fig ).

The loose fit has a negative effecton the stiffness of the bearing arrange-ment. The bearing ring with the loosefit can also begin to “wander”, whichcan wear the seating and lead to fret-ting corrosion and possibly “weld” the ring to its seating (➔ fig ).

The new solutionToday, the CARB toroidal roller bearingis available for the non-locating posi-tion in a self-aligning bearing system.It is no longer necessary to compro-mise.

4

3

2

1

1Fig

Fr

2Fig

0,2

0,1

0

3Fig

1

1,5

0,5

0

4Fig

Conventional solutionTwo spherical rollerbearings (or self-aligning ball bear-ings) compensateeasily for angularmisalignment of the inner ring withrespect to the outer ring

Induced internalaxial forces influ-ence the load distribution in the bearings

Load conditions in a conventionalsolutionChanges in axialforce in a non-locat-ing bearing duringthe machine start-upphase; internal axialforces of corres-ponding magnitudeare produced in thelocating bearing

In a non-locating bearing which has been clamped in itshousing bore seat-ing, high axialforces prevail in thebearing arrange-ment after the start-up phase and dra-matically shortenlife

Fa/Fr

Fa/Fr

t

t

Fr

9

1

5Fig

6Fig

7Fig

CARB toroidal roller bearings areable to compensate for misalignmentand accommodate axial displace-ments within the bearing as well (➔ fig

). This means that both rings of thenon-locating bearing can be axiallylocated in the housing and on the shaft(➔ fig ). If it is necessary to securethe rings so that they cannot “wan-der”, they can be mounted with aninterference fit, thus enhancing theradial stiffness of the bearing arrange-ment.

This is an optimal solution for appli-cations with undetermined load direc-tion, e.g. vibrating applications. Elim-ination of internal preload and preven-tion of wear in the housing is provided,i.e. no compromise between tight fitand axial freedom.

Axial displacement in a CARBtoroidal roller bearing takes place vir-tually without friction. No significantaxial internal forces occur (➔ fig ).The loads acting on the bearings aredetermined exclusively by the externalradial and axial forces. This meanslower resultant load on the bearingsand an improved load distributioncompared to the bearings in the con-ventional solution. Logically this implieslower operating temperatures, higheroperating viscosity and a much longerservice life as well as extended relubri-cation intervals and reduced mainten-ance costs (➔ fig ).

With the new solution, incorporatinga CARB toroidal roller bearing at thenon-locating side, the many excellentdesign characteristics and propertiesof the double row SKF spherical rollerbearings and self-aligning ball bearingscan be fully exploited. This providesnew opportunities to further optimizemachine design.

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6

6

5

The new solutionA spherical roller bear-ing or a self-aligningball bearing as thelocating bearing and a CARB toroidal rollerbearing as the non-locating bearing com-pensate for angularmisalignment of therings resulting fromerrors of alignment ordeflection under loadas well as thermalchanges in shaftlength, virtually with-out friction

No axial forces areinduced. The ringsof the non-locatingbearing should beaxially and radiallylocated

Lower operatingtemperatures extendrelubrication inter-vals and service life

1 Product information 2 Recommendations 3 Product dataSelf-aligning bearing system Page ............... 12 Page ............... 37

°C

Successful in service

Furthermore they not only provide self-alignment in the bearing arrange-ment, but also demonstrate extremelyhigh load carrying capacity.

One of the major application areasfor CARB toroidal roller bearings is insteelmaking and particularly in continu-ous casters with the multitude of guiderollers, which are subjected to themost difficult operating conditions.Paper machines are another importantapplication where shaft deflections and

Although a recent invention, the CARBtoroidal roller bearing has found ap-plications in many branches of indus-try. It has already proved itself and inmany cases the performance limitshave been appreciably extended. The bearings have fulfilled the promise of

• longer service life,• higher reliability,• reduced maintenance requirements

and• compact design

Main application areas• Steelmaking and rolling mills• Conveyors and roller beds • Paper machines • Fluid machinery • Crushers• Gearboxes of all types • Textile machines • Food and beverage

processing machines • Agricultural machinery• Vibrating screens

Major demands• Freedom• High load carrying capacity • High operational reliability• Long service life • Reduced maintenance• Low operational costs • Compact design • Enhanced performance • Technologically advanced• High power density

Solution

thermal changes in length of up to 10 mm have to be accommodated.

These are not the only fields whereCARB toroidal roller bearings performsuccessfully. They are also in servicein gearboxes, large electric motors,wind power plant, water turbines, bowthrusters, crane wheels, separators,centrifuges, presses, staking machinesfor tanneries, rotary cultivators andmulchers.

1 Product information 2 Recommendations 3 Product dataApplication areas Page ............... 12 Page ............... 37

To facilitate the incorporation ofCARB toroidal roller bearings in newas well as existing machines, to thebenefit of our customers, please con-sult the SKF application engineeringservice.

1 Product information 2 Recommendations 3 Product dataApplication areas Page ............... 12 Page ............... 37

Selection of bearing size

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To select the bearing size or determinebasic rating life of toroidal roller bear-ings it is possible to use all the knownand standardized (ISO 281) calculationmethods. However, it is recommendedthat the SKF Life Method be appliedso that the enhanced performance ofSKF bearings can be fully exploited.Detailed information can be found in theSKF General Catalogue in the section“Selection of bearing size” or in the“SKF Interactive Engineering Cata-logue” available on CD-ROM or onlineat www.skf.com.

The use of the SKF rating life equa-tion is very appropriate, in particular inself-aligning bearing systems, whereSKF Explorer spherical roller bearings,or a CARB and an SKF Explorer spher-ical roller bearing are used. In this wayan optimum arrangement can be de-signed and its system life calculatedusing the equation

whereLnm,Sys = SKF rating life for the bear-

ing system (at 100 – n %reliability), millions of revo-lutions

Lnm,SRB = SKF rating life for the locat-ing spherical roller bearing(at 100 – n % reliability), millions of revolutions

Lnm,CARB = SKF rating life for the non-locating CARB toroidalroller bearing (at 100 – n %reliability), millions of revo-lutions

Longer life or downsizingIn self-aligning bearing arrangementswhere toroidal roller bearings are usedat the non-locating side, there are noinduced internal axial forces. This is incontrast to the conventional self-align-ing bearing systems with two sphericalroller bearings or self-aligning ball bear-ings where the induced internal axialforces can be as much as 20 % ormore of the radial load acting on thenon-locating bearing. These additionalforces represent a sizeable proportionof the total load that cannot be neg-lected and can result in

• the bearing system not achieving therequisite life, or

• larger bearing being used to com-pensate for the additional forces.

Incorporating a CARB toroidal rollerbearing avoids induced axial loadsand the load conditions in the bearingarrangement can be accurately pre-dicted:

• the locating bearing is only subject-ed to its portion of the radial loadand the external axial forces, and

• the non-locating bearing is only subjected to its portion of the radialload.

Thus, a much more accurate bearingcalculation is possible. The benefitshave been confirmed in practice. Thenew self-aligning bearing systems –whether a spherical roller bearing (➔ diagram ) or a self-aligning ballbearing (➔ diagram ) is used as thelocating bearing – achieve a longerlife. It is also worth noting that, even if smaller bearings are used, it is oftenpossible to achieve system lives thatare longer compared to the traditionalsystems. This can be exploited by

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downsizing adjacent components andreducing costs.

To take full advantage of the bene-fits offered by the new self-aligningsystem it is necessary to carefullyselect the bearing size – at the non-locating as well as the locating side.SKF will assist in this if required.

1 Product information 2 Recommendations 3 Product dataPage................. 3 System life Page ............... 37

Lnm,Sys =9/8

√

11

+1

Lnm,SRB9/8 Lnm,CARB

9/8

13

2

1Diagram

2Diagram

Comparison of system lifes of a conven-tional self-aligning bearing system withtwo spherical roller bearings and self-aligning bearing systems incorporating a CARB toroidal roller bearing and a spherical roller bearing

Comparison of system lifes of a conven-tional self-aligning bearing system withtwo self-aligning ball bearings and self-aligning bearing systems incorporating a CARB toroidal roller bearing and a self-aligning ball bearing

Coefficient of friction µ

Coefficient of friction µ

Rel

ativ

e li

fe o

f the

sys

tem

Rel

ativ

e lif

e of

the

sys

tem

0 0,05 0,1 0,15* 0,2 0,25 0,3 0,35 0,40

1

C 3148 23148

C 3144 23144

23148 23148

0 0,05 0,1 0,15* 0,2 0,25 0,3 0,35 0,4

6

5

4

3

2

1

0

C 2222 2222

22222222

C 2220 2220

1 Product information 2 Recommendations 3 Product dataPage................ 3 System life Page ............... 37

* Typical value for steel on cast iron

* Typical value for steel on cast iron

0,5

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Design of bearing arrangements

1Fig 2Fig

Generally two bearings are required tosupport a rotating component, e.g. ashaft, in the radial and axial directionsand provide guidance and location relative to the stationary component,e.g. the housing: a locating bearingand a non-locating bearing. In the newSKF self-aligning bearing system aCARB toroidal roller bearing is used as the non-locating bearing and aspherical roller bearing (➔ fig ) or a self-aligning ball bearing (➔ fig )at the locating side.

Radial location In order to fully exploit the very highload carrying capacity of the toroidalroller bearing and as a consequenceits full life potential, the bearing ringsmust be fully and evenly supportedaround their whole circumference andacross the whole raceway width intheir seatings.

Choosing the fitsGenerally it is only possible to achievethe desirable radial location by an

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appropriate degree of interferencebetween the bearing rings and theirseatings. However, if easy mountingand dismounting are required, it is notusual to have an interference fit for theouter ring.

Recommendations for suitable shaftdiameter and housing bore tolerancesfor CARB toroidal roller bearings aregiven in tables , and . Theserecommendations apply to solid steelshafts and housings of cast iron orsteel.

Generally, CARB toroidal roller bear-ings follow the fit recommendationsfor spherical roller bearings on shaftsand in housings. However, a sphericalroller bearing on the non-locating sidemust be axially free, which requires aloose housing fit – this is not neededin bearing arrangements incorporatingCARB toroidal roller bearings. CARBbearings (and locating spherical rollerbearings) can therefore utilise theadvantages of tight outer ring fits ifmounting and dismounting allow this,but for normal, stationary outer ring loadit is not a necessity. For example K7 in a split housing for a fan with unbalanced

321

fan rotor or P7 in a non-split sugarshredder housing can be used.

Bearings with a tapered bore aremounted either direct on a taperedjournal or on adapter or withdrawalsleeves on cylindrical shaft seatings.The fit of the inner ring in these casesdepends on how far the ring is drivenup on the tapered seating.

Accuracy of associated componentsThe accuracy of the cylindrical seatingson shafts or in housing bores shouldcorrespond to that of the bearing. ForCARB toroidal roller bearings the shaftseating should be to tolerance grade 6and the housing seating to grade 7.For an adapter or withdrawal sleeve,wider diameter tolerances can beadopted for the cylindrical seating onthe shaft, e.g. grade 9 or 10.

The cylindricity as defined in ISO 1101-1996 for the bearing seatingshould be 1 or 2 grades better thanthe recommended dimensional toler-ance depending on the requirements.For example, a shaft seating machinedto tolerance m6 should have a cylin-dricity to grade 5 or 4.

SKF self-aligning bearing system with a spherical roller bearing at the locating side and a CARB toroidal roller bearingat the non-locating side

SKF self-aligning bearing system with a self-aligning ball bearing at the locating side and a CARB toroidal roller bearingat the non-locating side

1 Product information 2 Recommendations 3 Product dataPage................. 3 Radial location Page ............... 37

Conditions Examples Shaft diameter (mm) Toleranceover incl.

Bearings with cylindrical boreRotating inner ring load or direction of load indeterminate

Normal and General 40 k5heavy loads engineering, 40 65 m5(P > 0,06 C) electric motors, 65 100 m6

pumps, 100 140 n6gearboxes 140 280 p6

280 500 r61)500 r71)

Very heavy loads and shock loads 50 100 n61)with difficult working conditions 100 140 p61)(P > 0,12 C) 140 r61)

Bearings with tapered bore on adapter or withdrawal sleevesNormal loads and/or normal speeds h10/IT7/2Heavy loads and/or high speeds h9/IT5/2

Stationary inner ring loadEasy dismounting unnecessary h6Easy dismounting desirable g62)

1) Bearings with radial internal clearance greater than Normal may be necessary2) Tolerance f6 can be selected for large bearings to provide easy displacement

Conditions Examples Tolerance Remarks

Rotating outer ring loadHeavy loads and Crushers, N6 Bearing outside diameter < 160 mmshock loads vibrating P6 Bearing outside diameter ≥ 160 mm

screens, fans

Stationary outer ring loadLoads of all kinds General H7

engineering

Direction of load indeterminateHeavy shock loads M7

Normal and General K7heavy loads engineering,(P > 0,06 C) electric motors, H7 Easy mounting of bearing required

pumps

15

2

1Table

2Table

Conditions Examples Tolerance

Stationary outer ring load Loads of all kinds General H7

engineering

Direction of load indeterminateLoads of all kinds General J7

engineering,electric motors,pumps

3Table

Fits for solid steelshafts

Fits for non-splitcast iron and steelhousings

Fits for split castiron and steelhousings

1 Product information 2 Recommendations 3 Product dataPage................. 3 Radial location Page ............... 37

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4Fig

3Fig

Axial location The rings of CARB toroidal roller bear-ings should be axially located at bothsides on the shaft as well as in thehousing. It is recommended that thebearing rings be arranged so that theyabut a shoulder on the shaft or in thehousing. Inner rings can be locked inposition using

• a shaft (lock) nut (➔ fig ),• a retaining ring (➔ fig ) or • an end plate screwed to the shaft

end (➔ fig ).

Outer rings are usually secured inposition in the housing by the endcover (➔ fig ).

Instead of integral shaft and housingshoulders CARB toroidal roller bear-ings can be mounted against

• spacer sleeves (➔ fig ) or• retaining rings (➔ fig ).

Bearings with tapered bore that aremounted

• direct on a tapered journal are usu-ally secured by a nut on the thread-ed section (➔ fig ), or

• on an adapter sleeve and a steppedshaft are secured against a spacerring (➔ fig ), or

• on a withdrawal sleeve against a shaft shoulder are secured by a shaft nut (➔ fig ) or an endplate (➔ fig ).12

11

10

9

87

6

5

43

Abutment and fillet dimensionsThe abutment and fillet dimensions,which include the diameters of shaftand housing shoulders, spacer sleevesetc. have been determined so thatadequate abutment surfaces are pro-vided for the side faces of the bearingrings without any danger of the rotatingparts being fouled. The recommendedabutment and fillet dimensions for eachindividual bearing will be found in theproduct tables.

Axial location ofthe inner ring witha shaft nut

Axial location ofthe inner ring witha retaining ring

1 Product information 2 Recommendations 3 Product dataPage................. 3 Axial location Page ............... 37

1 Product information 2 Recommendations 3 Product dataPage................. 3 Axial location .... Page ............... 37

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2

5Fig

6Fig

7Fig

8Fig

9Fig

10Fig

11Fig

12Fig

Axial location ofthe inner ring withan end plate

Axial location ofthe outer ring withan end cover

Axial location withspacer sleeves

Axial location withretaining rings

Location of aCARB toroidalroller bearing on a tapered seatingby a shaft nut

CARB toroidalroller bearing onan adapter sleeveand a steppedshaft, axially located against a spacer ring

CARB toroidal roller bearing on a withdrawal sleeveand a steppedshaft, axially located by a shaft nut

CARB toroidal roller bearing on a withdrawal sleeveand a steppedshaft, axially located by an end plate

18

13Fig

14Fig

15Fig

16Fig

Design of adjacent components Space at the sides of the bearingTo enable axial displacement of theshaft relative to the housing it is neces-sary to provide space at both sides ofthe bearing as indicated in fig . Theactual value for the width of this spacecan be estimated based on

• the value Ca (from the producttables),

• the axial displacement of the bearingrings from the central position expected in operation, and

• the displacement of the rings causedby misalignment

Careq = Ca + 0,5 (s + smis)

or

Careq = Ca + 0,5 (s + k1 B α)

whereCareq = width of space required on each

side of the bearing, mmCa = minimum width of space required

on each side of the bearing, mm (➔ product tables)

s = thermal change in shaft length,mm

smis = axial displacement of rollercomplement caused by mis-alignment, mm

k1 = misalignment factor (➔ product tables)

B = bearing width, mm(➔ product tables)

α = angular misalignment, degrees

See also under “Axial displacement” onpage 40.

Normally, the bearing rings aremounted so that they are not dis-placed with respect to each other. How-ever, if considerable thermal changes in shaft length can be expected, theinner ring can be mounted offset rela-tive to the outer ring up to the permis-sible axial displacement s1 or s2 in thedirection opposite to the expectedthermal elongation (➔ fig ). In thisway, the permissible axial displace-ment can be appreciably extended, anadvantage which is made use of in thebearing arrangement of drying cylin-ders in papermaking machines.

14

13

Free space at both sides of thebearing

By mounting theouter ring pur-posely displacedwith regard to theinner ring the permissible axialdisplacement canbe extended

CARB toroidalroller bearing on a tapered journalwith oil duct anddistributor groove

CARB toroidalroller bearingarrangement withoil ducts and dis-tributor grooves inthe shaft andhousing

It is particularly important whendesigning large bearing arrangementsto take steps so that the mounting anddismounting of the bearings are facili-tated or actually made possible.

1 Product information 2 Recommendations 3 Product dataPage................. 3 Associated components Page ............... 37

Ca

s1s2

19

2

Recommended dimensions for oil ducts and distributor grooves Threaded connection holes

Bearing seating Dimensionsdiameter ba ha ra Nover incl.

mm mm

100 3 0,5 2,5 2,5100 150 4 0,8 3 3150 200 4 0,8 3 3

200 250 5 1 4 4250 300 5 1 4 4300 400 6 1,25 4,5 5

400 500 7 1,5 5 5500 650 8 1,5 6 6650 800 10 2 7 7

800 1 000 12 2,5 8 8

4Table

Thread Design DimensionsGa Gb Gc

1) Namax

– – mm

M 6 A 10 8 3

G 1/8 A 12 10 3

G 1/4 A 15 12 5

G 3/8 B 15 12 8

G 1/2 B 18 14 8

G 3/4 B 20 16 8

1) Effective threaded length

5Table

L3

L

N

hara

ba Na

Ga

c bG G

Na

Gac

b

G

G60°

Design A Design B

Threaded holes for the oil injectionmethodIf the oil injection method is to be used

• for mounting and dismounting bearings on tapered journals (➔ fig ) or

• for dismounting bearings on or in cylindrical seatings on the shaft or in the housing

it is necessary to provide oil ducts anddistributor grooves in the seating onthe shaft or in the housing (➔ fig ).The distance of the distributor groovefrom the side at which the bearing is tobe mounted and/or dismounted shouldcorrespond to approximately a third ofthe bearing width. Recommended

16

15

dimensions for the distributor grooves,the oil ducts and the appropriatethreads for the connections are givenin tables and .54

1 Product information 2 Recommendations 3 Product dataPage................. 3 Associated components Page ............... 37

20

ReferenceMore information on radial shaftseals, V-ring seals or mechanicalseals will be found in the SKF catalogue 4006 “CR seals” or inthe “SKF Interactive EngineeringCatalogue” on CD-ROM or onlineat www.skf.com.

CR seals

Sealing the bearingarrangementWhen selecting the most suitable seal-ing for the non-locating bearing ar-rangement of a self-aligning bearingsystem it is necessary to pay particu-lar attention to

• the angular misalignment of theshaft and

• the magnitude of the axial displacement.

Otherwise the general selection criteriapresented in the SKF General Cata-logue (and the “SKF Interactive Engin-eering Catalogue”) apply and all typesof seal can be used.

Non-rubbing seals are to be pre-ferred when the operating conditionsinvolve

• high speeds,• large axial displacements,• high temperatures,

and the sealing position is not directlyexposed to contamination. The shaftshould be horizontal.

The simple gap-type seal (➔ fig )is very suitable for sealing the non-locating arrangement of self-aligningbearing systems. The size of the gapcan be adapted to the misalignment ofthe shaft and is not limited in any way.

Single or multi-stage labyrinth sealsare obviously more efficient than thesimple gap-type seal, but are moreexpensive to produce. With CARBtoroidal roller bearings, the labyrinthpassages should be arranged axially in order to provide freedom of axialmovement for the shaft in operation. Ifconsiderable misalignment is expect-ed in operation, the passages shouldbe angled (➔ fig ). When split hous-ings are used, labyrinth seals withradially arranged passages can beused, provided axial movement of theshaft relative to the housing is not limited (➔ fig ).

Radial shaft seals are rubbing sealsand are also eminently suitable for seal-ing grease or oil lubricated CARBtoroidal roller bearings, provided mis-alignment is slight and the seal lip coun-terface is sufficiently wide (➔ fig ).20

19

18

17

Some of the seal types mentionedhere are supplied as standard withSKF bearing housings and include a double-lip rubbing seal, a labyrinth seal as well as a Taconite seal (➔ fig

). Further details will be found inthe brochure 4403 “SNL plummerblock housings solve the housingproblems”.

21

1 Product information 2 Recommendations 3 Product dataPage................. 3 Seals Page ............... 37

21

2

18Fig

19Fig

20Fig

21Fig

17Fig Gap-type seal

Labyrinth sealwith angled passages

Labyrinth sealwith radiallyarranged passages

Radial shaft seal

Taconite seal

1 Product information 2 Recommendations 3 Product dataPage ................. 3 Seals Page ............... 37

22

1FigCARB toroidal roller bearings can belubricated with grease as well as oil.There is no strict rule for when greaseor oil should be used.

Grease has the advantage over oilthat it is more easily retained in thebearing than oil and grease is better ifthe shaft is at an angle or arrangedvertically.

On the other hand, oil lubricationallows higher operating speeds andtemperatures and can contribute toheat removal from the bearing position,which is particularly important whereexternal heating is involved. Very smallquantities of lubricant are required tolubricate the bearing surfaces.

Since CARB toroidal roller bearingscannot be relubricated via the outerring, lubricant has to be supplied fromthe side of the bearing. This is bestdone via a duct that opens immediatelyadjacent to the side face of the bear-ing outer ring. To force the lubricant topass through the bearing, a drainageopening should be provided at theopposite side of the bearing (➔ fig ).

Grease lubricationFor the lubrication of CARB toroidalroller bearings good quality rustinhibiting greases that are resistant to ageing and have a consistency of 2 or 3 are suitable. Many factors influ-ence the choice of grease. To assist inthis process, SKF greases that aresuitable for CARB bearing lubricationare listed in table .1

1

Recommended SKF greases

Lubrication

Operating conditions SKF greaseDesignation Temperature Viscosity at

range 40/100 ˚C

– – ˚C mm2/s

Standard bearing LGMT 2 –30/+120 110/11arrangements

Standard bearing arrange- LGMT 3 –30/+120 125/12ments but with relativelyhigh ambient temperatures

Operating temperatures LGHB 2 –20/+150 420/26,5always over 100 ˚C

High operating temperatures, LGHP 2 –40/+150 96/10,5smooth operation

Shock loads, heavy loads, LGEP 2 –20/+110 200/16vibration

High demands on LGGB 2 –40/+120 110/13environmental friendliness

Full details on the mentioned SKF greases as well as the complete range of SKF greases will be found in– SKF catalogue MP3000 “SKF Maintenance and Lubrication Products” or online at www.mapro.skf.com – “SKF Interactive Engineering Catalogue” on CD-ROM or online at www.skf.com

1Table

The correct quantity of greaseFor the majority of applications the following guidelines apply:

• Caged CARB toroidal roller bearingsshould be filled with grease toapproximately 50 %. In bearingsthat are to be greased beforemounting it is recommended just tofill the space between the inner ringand the cage (➔ fig ).

• The free space in the bearing hous-ing should be filled with grease tobetween 30 and 50 %.

• Full complement CARB toroidalroller bearings should be completelyfilled with grease.

For bearing arrangements that turnslowly but where good protectionagainst corrosion is required, all thefree space in the housing can be filledwith grease as there is little risk of theoperating temperature increasing.

2

Lubricant supply to the bearing

1 Product information 2 Recommendations 3 Product dataPage................. 3 Grease lubrication ....................Page 37

23

2

2Fig

Bearing grease fillCaged CARB toroidal roller bearings shouldnot be completely filled with grease; forhigh speed operation fill only the spacebetween the inner ring and the cage

The tf value is then derived consider-ing the load magnitude, given by thevalue of C/P. The relubrication interval(tf) is an estimated value, valid for anoperating temperature of 70 °C, usinggood quality lithium base greases.

Different conditions are covered indetail in “Deviating conditions”.

If the value of “n × dm” approachesthe limit value (> 70 %) or if ambienttemperatures are high, then the use of

300 000 400 000100 000 600 000

1 000

100

C/P ≥ 15

C/P ≈ 8

C/P ≈ 4

10 000

100 000

200 000 500 000 700 000 800 000

500

5 000

50 000

0

1Diagram

Example: CARB toroidal roller bearing C 2220 KThe bearing has a bore diameter d = 100 mm, an outside diameter D = 180 mm and rotates at a speed n = 1 000 r/min. The load ratio C/P is 4 and the operating temperature lies between 60 and 70 °C. What is therelubrication interval?

The bearing factor n × dm is obtained as follows: n × dm = 1 000 × 0,5 (d + D) = 1 000 × 0,5 (100 + 180) = 140 000. Follow a vertical line from the x-axis from the point n × dm = 140 000 until it intersects the line of the load ratio C/P = 4. The relubrication interval can then be read off on the y-axis by drawing a horizontal line from the point of intersection with 3 000 operating hours.

Bearing factor n × dm

Relubrication intervals for CARB toroidal roller bearings at 70 °C

1 Product information 2 Recommendations 3 Product dataPage ................. 3 Grease lubrication Page ............... 37

t f,op

erat

ing

hour

sRelubricationCARB toroidal roller bearings have to be relubricated if the service life of thegrease is shorter than the expected ser-vice life of the bearing. Relubricationshould always be undertaken at a timewhen the existing lubrication is still satis-factory.

The time at which relubrication shouldbe undertaken depends on many relatedfactors. These include bearing type andsize, speed, operating temperature,grease type, space around the bearingand the bearing environment.

It is only possible to base recommen-dations on statistical rules; the SKFrelubrication intervals are defined as thetime period, at the end of which 99 % ofthe bearings are still reliably lubricated.This represents L1 for grease life.

SKF recommends using experiencedata from running applications andtests, together with the estimated relu-brication intervals provided in the nextsection.

Relubrication intervals (tf)The relubrication intervals tf for normaloperating conditions are provided indiagram . The diagram is valid forbearings on horizontal shafts underclean conditions.

The value on the horizontal axis isobtained from “n × dm” (rotationalspeed × bearing mean diameter) (unit: mm/min) multiplied by the relevantCARB toroidal roller bearing factor,which depends on the applied CARBtoroidal roller bearing execution andloading situation. The bearing factorand recommended maximum “n × dm”values for CARB toroidal roller bearingsare given in table .2

1

Bearing execution Bearing Maximum n × dmfactor C/P ≥ 15 C/P ≈ 8 C/P ≈ 4

CARB bearings with cage 2 350 000 200 000 100 000CARB bearings – full complement1) 4 N.A3) N.A3) 20 0002)

1) The tf value obtained from diagram 1 needs to be divided by a factor 10 2) For higher speeds oil lubrication is recommended 3) For these C/P valves a caged bearing is recommended instead

2Table

Bearing factors and recommended maximum speed limits

the calculations presented in the SKFGeneral Catalogue, section “Speedsand vibration”, is recommended tocheck the operating temperature andthe proper lubrication method.

24

3Fig 4Fig

Grease valveExcess grease is caused to enter a circular channel in the housing cover

Supplying grease to a CARB bearingWhen using a hand-operated grease gun, excess pressure shouldbe avoided as otherwise the seals may be damaged

Deviating conditionsOperating temperatureTo take account of the accelerated ageing of the grease with increasingtemperature, SKF recommends halvingthe intervals obtained from the diagramfor every 15 °C increase in bearing tem-perature above 70 °C.

The relubrication interval tf may beextended at temperatures below 70 °C.In many cases the interval may also beprolonged if the load is low (C/P = 30 to50). A total prolongation of the relubri-cation interval tf by more than a factortwo is not recommended.

For full complement bearings, tfvalues obtained from the diagramshould not be prolonged.

Moreover, it is not advisable to userelubrication intervals in excess of 30 000 hours.

For many applications, there is apractical grease lubrication limit, whenthe bearing ring with the highest tem-perature reaches an operating tempera-ture of 100 °C. Above this temperaturespecial greases should be used. Inaddition,temperature stability of thebearing and premature seal failureshould be taken into consideration.

For high temperature applications,contact the SKF application engin-eering service.

Vertical shaftFor bearings on vertical shafts, theintervals obtained from the diagramshould be halved.

The use of good sealing or a retain-ing shield is a prerequisite or greasewill leak from the bearing arrangement.

VibrationsMild vibrations will not have a negativeeffect on grease life, but at high vibra-tion and shock levels, such as those invibrating screen applications, will causethe grease to churn. In these cases therelubrication interval should be reduced.If the grease becomes too soft, agrease with a better mechanical stability(e.g. LGHB 2) and/or a stiffer grease(NLGI 3) should be used.

Outer ring rotationIn applications where there is outer ringrotation, the value of the bearing factorn × dm is calculated by applying thevalue of the bearing outside diameter Dinstead of dm. The use of a good seal-ing mechanism is a prerequisite in orderto avoid grease loss.

Under conditions of high outer ringspeeds (i.e. > 50 % of the speed rat-ing in the bearing tables), greases witha reduced bleeding tendency shouldbe selected (e.g. lithium complex andpolyurea).

ContaminationIn case of ingress of contamination, amore frequent relubrication interval willreduce the negative effects of foreignparticles on the bleeding characteristicsof grease while reducing the damagingeffects caused by overrolling of par-ticles. Fluid contaminants (water, pro-cess fluids) also call for a reduced inter-val. In case of severe contamination,continuous relubrication should be considered.

Requisite grease quantities for relubricationThe used grease in a CARB toroidalroller bearing should be replaced byfresh grease. The quantity of greaserequired for this depends on the bear-ing size; this can be determined using

Gp = 0,005 D B

whereGp = grease quantity required for

periodic lubrication, gD = bearing outside diameter, mmB = bearing width, mm

1 Product information 2 Recommendations 3 Product dataPage................. 3 Grease lubrication Page ............... 37

25

2

5Fig

Oil level in CARBtoroidal rollerbearing arrange-mentsMax.: middle of thelowest rollerMin.: 2 to 3 mmabove the lowestpoint of the outerring smallest diam-eter, D1 in the product tables

1 Product information 2 Recommendations 3 Product dataPage................. 3 Oil lubrication Page ............... 37

Grease valveIf CARB toroidal roller bearings are tobe relubricated frequently, there is arisk that too much grease will collect inthe housing. This risk can be avoidedby using a grease valve that allowsexcess grease to leave the housing (➔ fig ).

The so-called grease valve consistsof a washer that rotates with the shaftand forms a narrow gap to the housingcover. Excess grease is carried by thewasher into this gap and leaves thehousing by a grease escape hole inthe base.

The grease should always be supplied at the side of the bearingopposite to the grease valve so that itis forced to pass through the bearing.When the bearing is mounted on anadapter sleeve, the lock nut with lock-ing washer acts as a grease valve, so that grease should be supplied atthe side opposite to the lock nut (➔ fig ).4

3

Oil lubricationOil lubrication is recommended ormust be used if

• the relubrication intervals for greaselubrication are too short,

• speeds and/or operating tempera-tures are too high for grease lubrication,

• heat must be removed from thebearing position, or

• adjacent components are lubricatedwith oil.

For CARB toroidal roller bearingsthe following methods are normallyemployed:

• Oil bath lubrication where the oil isdistributed by rotating machinecomponents to the bearing arrange-ment and runs back to the sump.

• Circulating oil lubrication where thecirculation is achieved by a pumpand where the oil is filtered andcooled before being returned to the sump. The use of this methodrequires efficient sealing to preventoil leakage.

The oil level should be checked regu-larly. The appropriate level should notbe higher than the middle of the low-est roller when the bearing is station-ary.

The lower limit should be 2 to 3 mmabove the lowest point of the outerring smallest diameter, D1 in the producttables (➔ fig ).

The same oils can be used for CARBtoroidal roller bearings as for sphericaland cylindrical roller bearings. Theyshould

• have good thermal and chemicalstability,

• contain anti-wear additives and• provide good protection against

corrosion.

Oils of viscosity class

• ISO VG 150 and ISO VG 220 can beused under normal conditions and

• ISO VG 320 and VG 460 may bemore appropriate at high tempera-tures, under heavy loads and slowspeeds.

5

26

1Fig 2Fig

Mounting dolly with abutment faces for both bearing rings in the same plane

A CARB toroidal roller bearing on aninduction heater

The tools to assist mounting CARBtoroidal roller bearings, depending onsize, include mechanical or hydraulicequipment as well as various heaters.The basic rule is to avoid blows direct-ed towards the bearing rings, cages orrollers.

Detailed information on mountingrolling bearings will be found in thepublication 4100 “SKF BearingMaintenance Handbook”, as well asonline at www.skf.com/mount.

Mounting on cylindricalseatingsWith CARB bearings, the ring that is tohave the tighter fit should be mountedfirst. If the bearing is to be mounted onthe shaft and in the housing at thesame time a tool of the type shown infig should be used, which abutsboth bearing rings in the same plane.

As a rule, larger bearings cannot bemounted in a cold state, as the forcerequired to press the bearing on to orin to a cylindrical seating increasesconsiderably with increasing size.Therefore it is recommended

• to heat the bearing before it ismounted on the shaft, and

• to heat non-split housings beforeinserting the bearing.

1

For mounting on the shaft a tempera-ture differential of 80 °C (betweenambient temperature and heated innerring) is usually sufficient. For housingsthe appropriate differential depends onthe degree of interference and theseating diameter and generally moder-ate temperature increases will suffice.An even and risk-free heating of CARBbearings can be achieved using aninduction heater (➔ fig ).2

Mounting

1 Product information 2 Recommendations 3 Product dataPage................. 3 Cylindrical seating Page ............... 37

27

2

Bearing Clear- Axial Turningdesig- ance drive-up angle nation reduc- α

tion

– mm mm degrees

C 2205 0,011 0,42 100C 2206 0,013 0,45 105C 2207 0,016 0,48 115C 2208 0,018 0,52 125C 2209 0,020 0,54 130

C 2210 0,023 0,58 140C 2211 0,025 0,60 110C 2212 0,027 0,65 115C 2213 0,029 0,67 120C 2214 0,032 0,69 125

C 2215 0,034 0,72 130C 2216 0,036 0,77 140C 2217 0,038 0,80 145C 2218 0,041 0,84 150C 2219 0,043 0,84 150

C 2220 0,045 0,87 155C 2222 0,050 0,95 170

C 2314 0,032 0,72 130C 2315 0,034 0,75 135C 2316 0,036 0,78 140C 2317 0,038 0,81 145C 2318 0,041 0,86 155

C 2319 0,043 0,87 155C 2320 0,045 0,90 160

1Table

3

Move the blade backwards and forwardsbetween roller and outer ring

4Fig

Measuring clearance reduction

Mounting on taperedseatingsCARB toroidal roller bearings withtapered bore are always mounted onthe shaft with an interference fit. Todetermine the degree of interferenceeither the reduction in radial internalclearance or the amount by which theinner ring is driven up on its seatingcan be used.

Suitable methods for mountingCARB bearings with tapered bore are:

• measuring the clearance reduction,• measuring the lock nut tightening

angle,• measuring the axial drive-up and• measuring the inner ring expansion.

For CARB toroidal roller bearings withbore diameters of 50 mm and above itis recommended that the SKF Drive-upMethod is applied. This method ismore accurate and takes less timethan the procedure based on clear-ance reduction.

Measuring clearance reductionIn this case, the initial radial internalclearance must be measured. Feelergauges should be used. The clearanceshould always be measured betweenthe outer ring and an unloaded roller.Before measuring, the bearing shouldbe rotated a few times to make surethat the rollers have assumed theircorrect position. For the first measure-ment a blade should be selected that

is slightly thinner than the minimumvalue for the clearance. During themeasurement, the blade should bepushed backwards and forwards (➔ fig ) until it can be inserted to themiddle of the roller. The procedureshould be repeated using slightlythicker blades each time until a certainresistance is felt.

During mounting, the reduction inclearance should be measured be-tween the outer ring raceway and the lowest roller (➔ fig ). Again thebearing should be rotated a few timesbetween each measurement.

Guideline values for the clearancereduction and axial drive-up are given intable on page 28. They are valid forsolid steel shafts and normal operatingconditions (C/P > 10). Where loads areheavy (C/P < 5), speeds high or there isa considerable temperature gradientacross the bearing, greater clearancereductions or axial drive-up are requiredand thus bearings with greater initialradial internal clearance might be needed.

The minimum values given in tableon page 28 for the clearance reduc-

tion apply mainly to bearings having initial clearances close to the lower limits for clearance given in tableon page 39. This will make sure that thefinal clearance will not be less than thepermissible minimum. For bearings withC3 or C4 clearance to have a sufficientdegree of interference on their seating, it is recommended that the maximumclearance reductions be applied.

2

2

2

4

3

1 Product information 2 Recommendations 3 Product dataPage................. 3 Tapered seating Page ............... 37

Fig

Measuring the lock nut tighteningangleSmaller bearings can easily be mount-ed using the tightening angle α throughwhich the nut has to be turned to driveup the bearing properly on to its taperedseating. For the CARB toroidal rollerbearings in question the tighteningangle α is listed in table . Beforemounting, the thread and side face ofthe nut should be smeared with amolybdenum disulphide paste or simi-lar lubricant and the seating should belightly oiled with thin oil. The bearing is

1

Angular drive-up for CARB bearings

α

180°

Bearing bore Reduction of Axial drive-up s1) Permissible residualdiameter radial internal Taper Taper radial clearance2)d clearance 1:12 1:30 after mounting

bearings with initial clearance

over incl. min max min max min max Normal C3 C4

mm mm mm mm

24 30 0,012 0,018 0,25 0,34 0,64 0,85 0,025 0,033 0,04730 40 0,015 0,024 0,30 0,42 0,74 1,06 0,031 0,038 0,05640 50 0,020 0,030 0,37 0,51 0,92 1,27 0,033 0,043 0,063

50 65 0,025 0,039 0,44 0,64 1,09 1,59 0,038 0,049 0,07465 80 0,033 0,048 0,54 0,76 1,36 1,91 0,041 0,055 0,08880 100 0,040 0,060 0,65 0,93 1,62 2,33 0,056 0,072 0,112

100 120 0,050 0,072 0,79 1,10 1,98 2,75 0,065 0,083 0,129120 140 0,060 0,084 0,93 1,27 2,33 3,18 0,075 0,106 0,147140 160 0,070 0,096 1,07 1,44 2,68 3,60 0,085 0,126 0,173

160 180 0,080 0,108 1,21 1,61 3,04 4,02 0,093 0,140 0,193180 200 0,090 0,120 1,36 1,78 3,39 4,45 0,103 0,150 0,209200 225 0,100 0,135 1,50 1,99 3,74 4,98 0,113 0,163 0,228

225 250 0,113 0,150 1,67 2,20 4,18 5,51 0,123 0,175 0,251250 280 0,125 0,168 1,85 2,46 4,62 6,14 0,133 0,186 0,276280 315 0,140 0,189 2,06 2,75 5,15 6,88 0,143 0,198 0,292

315 355 0,158 0,213 2,31 3,09 5,77 7,73 0,161 0,226 0,329355 400 0,178 0,240 2,59 3,47 6,48 8,68 0,173 0,251 0,358400 450 0,200 0,270 2,91 3,90 7,27 9,74 0,183 0,275 0,383

450 500 0,225 0,300 3,26 4,32 8,15 10,80 0,210 0,295 0,433500 560 0,250 0,336 3,61 4,83 9,04 12,07 0,225 0,327 0,467560 630 0,280 0,378 4,04 5,42 10,09 13,55 0,250 0,364 0,508

630 710 0,315 0,426 4,53 6,10 11,33 15,25 0,275 0,386 0,560710 800 0,355 0,480 5,10 6,86 12,74 17,15 0,319 0,430 0,620800 900 0,400 0,540 5,73 7,71 14,33 19,27 0,335 0,465 0,675

900 1 000 0,450 0,600 6,44 8,56 16,09 21,39 0,364 0,490 0,7401 000 1 120 0,500 0,672 7,14 9,57 17,86 23,93 0,395 0,543 0,8231 120 1 250 0,560 0,750 7,99 10,67 19,98 26,68 0,414 0,595 0,885

1) Only valid for solid steel shafts2) The residual clearance must be measured when the initial radial internal clearance (before mounting) lies in the lower

half of the clearance range and if large temperature differences between inner and outer rings are to be expected inoperation; the residual clearance should not be less than the minimum values quoted here. When measuring clearancecare must be taken to see that both bearing rings and the roller complement are centrically arranged with respect toeach other

2Table

28

then pushed on to the tapered seatingand the nut screwed on. By turning thenut through the recommended angle αthe bearing will be pressed up on thetapered seating. As the bearing has atendency to skew when being pressedup it is advisable to re-position thehook spanner in a slot at 180° to thatused for tightening and then apply alight hammer blow to the spanner. Thebearing will straighten up on its seat-ing. Finally the residual clearance ofthe bearing should be checked.

In all cases, before mounting, therust inhibiting oil should be wiped fromthe bore and outside diameter of newbearings and sleeves. The shaft seat-ing and outside diameter of the sleeveshould then be lightly oiled with thin oil.

The SKF Drive-up MethodThe SKF Drive-up Method is based onmeasuring an axial displacement ofthe bearing inner ring on its taperedseating from a reliably determinedstarting position.

The SKF Drive-up Method (➔ fig )requires the use of an HMV..E hydraulicnut, that can take a dial gauge. A pres-sure gauge, appropriate to the mount-ing conditions, mounted on a suitablysized hand pump, allows accurate pres-sure measurement to determine thestarting position. The tools required areshown in fig .

Guideline values for

• the requisite oil pressure and • the axial displacement

for the individual bearings are given intable on page 30.3

6

5

s

Guideline values for clearance reductionand axial drive-up


One sliding interfaceCase 1

One sliding interfaceCase 2

Two sliding interfacesCase 3

Two sliding interfacesCase 4

29

2

5Fig

6Fig

Suitable tools for the SKFDrive-up Method

1. Check whether the bearing size and the HMV .. E hydraulic nut coincide. Otherwisethe values for the pressure given in table 2 must be adjusted (➔ note on page 32).

2. Check the number of sliding interfaces (➔ above).

3. Lightly coat the sliding surfaces with a thin oil, e.g. SKF LHMF 300, and place thebearing on the tapered journal or sleeve. Screw the hydraulic nut on to the thread ofthe journal or sleeve so that it abuts the bearing and connect the appropriate oilpump (➔ fig ).

4. Bring the bearing to its starting position. Pump oil into the hydraulic nut until thepressure quoted in table on page 30 is reached.

5. Set the dial gauge to “zero” (➔ fig ) and pump more oil into the hydraulic nut untilthe bearing has been driven up the distance prescribed in table on page 30 and isin its final position.

6. After mounting has been completed, release the return valve of the oil pump, so that oil under high pressure in the nut can flow back out of the nut.

7. To completely empty the oil, bring the piston of the hydraulic nut to its original position. This is most simply done by screwing the nut further up the threaded portion of the journal or sleeve.

8. Remove the nut from the shaft by unscrewing and replace with a lock nut and a locking device.

36

3

6

Dial gauge

SKF hydraulic nut HMV .. E

SKF pump 729124 SRB (for nuts up to and including HMV 54 E)SKF pump TML 50 SRB (for nuts up to and including HMV 170 E)

The SKF Drive-up Method

s

s

s

Zeroposition

Startingposition

Finalposition


30

Basic bearing Starting position Final position Hydraulic nut designation Requisite oil pressure for Axial displacement from Radial clearance Desig- Piston

one sliding two sliding starting position reduction from nation areainterface* interfaces* one sliding two sliding zero position

interface* interfacesss ss ∆r

– MPa mm mm – mm2

Series C 22C 2210 K 0,67 1,15 0,34 0,41 0,023 HMV 10 E 2 900C 2211 K 0,57 0,98 0,35 0,42 0,025 HMV 11 E 3 150C 2212 K 1,09 1,86 0,39 0,47 0,027 HMV 12 E 3 300

C 2213 K 0,82 1,40 0,40 0,47 0,029 HMV 13 E 3 600C 2214 K 0,76 1,29 0,43 0,50 0,032 HMV 14 E 3 800C 2215 K 0,70 1,20 0,45 0,52 0,034 HMV 15 E 4 000





C 2244 K 1,95 3,34 1,15 1,22 0,100 HMV 44 E 14 400



C 2320 K 2,56 4,36 0,59 0,66 0,045 HMV 20 E 5 100C 2326 K 2,71 4,62 0,73 0,81 0,059 HMV 26 E 6 400







* The quoted values are for hydraulic nuts, the thread diameter of which corresponds to the bore diameter of the bearing to be mounted and for applications with lightly oiled slidingsurfaces

3Table


31

2







C 30/500 K 1,56 2,66 2,47 2,54 0,225 HMV 100 E 51 500C 30/530 K 1,54 2,63 2,60 2,68 0,239 HMV 106 E 56 200C 30/560 K 2,26 3,85 2,84 2,91 0,252 HMV 112 E 61 200




C 30/1000 K 1,93 3,30 4,85 4,92 0,450 HMV 200 E 145 800








Series C 31C 31/500 K 3,54 6,04 2,57 2,64 0,225 HMV 100 E 51 500C 31/530 K 3,40 5,81 2,71 2,79 0,239 HMV 106 E 56 200C 31/560 K 3,11 5,30 2,83 2,90 0,252 HMV 112 E 61 200



3Continuation table


32





Series C 31


C 31/850 K 4,02 6,86 4,32 4,39 0,383 HMV 170 E 114 600C 31/1000 K 3,69 6,30 4,97 5,04 0,450 HMV 200 E 145 800

Series C 32C 3224 K 2,46 4,20 0,69 0,76 0,054 HMV 24 E 6 000C 3232 K 2,68 4,58 0,87 0,94 0,072 HMV 32 E 8 600

C 3234 K 3,87 6,60 0,96 1,03 0,076 HMV 34 E 9 400C 3236 K 3,69 6,30 1,01 1,09 0,081 HMV 36 E 10 300

Series C 39C 3972 K 0,63 1,08 1,74 1,81 0,162 HMV 72 E 31 300C 3976 K 1,06 1,81 1,88 1,95 0,171 HMV 76 E 33 500C 3980K 0,74 1,27 1,93 2,00 0,180 HMV 80 E 36 700


C 3996 K 1,18 2,01 2,37 2,44 0,216 HMV 96 E 48 600C 39/500 K 0,95 1,63 2,43 2,50 0,225 HMV 100 E 51 500C 39/530 K 0,73 1,25 2,52 2,59 0,239 HMV 106 E 56 200




C 39/950 K 1,04 1,77 4,50 4,57 0,428 HMV 190 E 135 700


3Continuation table

NoteThe values given in table for therequisite oil pressure and the axialdisplacement ss apply to bearings tobe mounted on solid steel shafts forthe first time. For the case shown in fig on page 29 (Case 4) “Bearingon withdrawal sleeve”, the guidelinevalues given in table do notapply as a smaller nut is used thanthat shown for the bearing in

3

5

3 table . The requisite oil pressure canbe calculated from

AreqPreq = · Pref

Aref

where Preq = requisite oil pressure for

hydraulic nut used, MPa

3 Pref = oil pressure specified for thestandard hydraulic nut (➔ table ), MPa

Areq = piston area of hydraulic nutused (➔ table ), mm2

Aref = piston area of the specifiedstandard hydraulic nut (➔ table ), mm23

3

3


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2

1 Product information 2 Recommendations 3 Product dataPage..................3 SKF Drive-up Method Page … … …37

Measuring the inner ring expansionMeasuring inner ring expansion allowslarge size CARB bearings with atapered bore to be mounted simply,quickly and accurately without meas-uring the radial internal clearancebefore and after mounting. The SKFSensorMount® Method uses a sensor,integrated with the CARB toroidalroller bearing inner ring, and a dedi-cated hand-held indicator (➔ fig ).

The bearing is driven up the taperedseating using common SKF mountingtools. Information from the sensor isprocessed by the indicator. Inner ringexpansion is displayed as the relationbetween the clearance reduction (mm)and the bearing bore diameter (m).

Aspects like bearing size, smooth-ness, shaft material or design – solid orhollow do not need to be considered.

For detailed information about SKFSensorMount please contact SKF.

7

Additional mounting informationAdditional information on mountingCARB toroidal roller bearings can befound

• in the handbook “SKF Drive-upMethod” on CD-ROM,

• in the “SKF Interactive EngineeringCatalogue” on CD-ROM or online atwww.skf.com, or

• online at www.skf.com/mount.

ON0FF

CLR MAX

0,450

TMEM 1500SensoMount Indicator

7Fig

34

1 Product information 2 Recommendations 3 Product dataPage................. 3 Cylindrical seating Page ............... 37

If CARB toroidal roller bearings are tobe re-used after dismounting, theforce used for dismounting on noaccount should pass through therollers. The ring with the looser fitshould be withdrawn from its seatingfirst. There are three methods availableto dismount the bearing ring that hasbeen mounted with an interference fit:mechanical, hydraulic or the oil injec-tion method.

Detailed information on the dis-mounting of bearings is contained inpublication 4100 “SKF Bearing Main-tenance Handbook”.

Dismounting from a cylindrical seatingCARB toroidal roller bearings having a bore diameter up to approximately120 mm that have been mounted withan interference fit on the shaft can beremoved using a conventional puller.The puller should be applied to theface of the ring to be dismounted (➔fig ). By turning the puller spindlethe bearing is easily removed from thecylindrical seating.

For larger bearings, the withdrawalforces are considerable and in suchcases the use of pullers with hydraulicassistance (➔ fig ) or of the SKF oilinjection method is to be preferred.

CARB toroidal roller bearings thathave an interference fit for both ringsshould preferably pressed out of thehousing together with the shaft. On theother hand it is also possible to with-draw the bearing with the housing fromthe shaft, particularly if the oil injectionmethod can be applied (➔ fig ).

Small CARB toroidal roller bearingsmounted with an interference fit in ahousing bore without shoulders canbe removed using a dolly applied tothe outer ring. Larger bearings require

3

2

1

1Fig

3Fig

2Fig

Dismounting

The puller isapplied to the sideface of the innerring

SKF puller with hydraulicassistance

CARB toroidalroller bearing on acylindrical seatingbeing removedusing the oil injection method

35

2

more force to remove them and apress is required.

Various larger CARB toroidal rollerbearings that have a loose or a transi-tion fit in the housing can be removedusing a tool with hooks that passbetween the rollers and grip the outerring from behind (➔ fig ), so that thewithdrawal forces are applied directlyto the outer ring and the rollers do notbecome jammed between the rings.

Dismounting from a tapered seatingAs bearings with tapered bore comefree from their seating very suddenly itis necessary to provide a stop of somesort to limit their axial movement. Anend plate screwed to a shaft end or alock nut (➔ fig ) serve this purpose.The lock nut should be unscrewed afew turns.

Small CARB toroidal roller bearingscan be removed with the aid of a dollyor a drift of special design (➔ fig ).A few blows directed at the dolly aresufficient to drive the inner ring fromits tapered seating.

Medium-sized CARB toroidal rollerbearings can be withdrawn using amechanical puller or one with hydraulicassistance. To avoid damage to thebearing, the puller should be appliedcentrically.

The removal of large bearings isgreatly facilitated if the oil injectionmethod is employed.

.

6

5

4

4Fig

Schematic sketch of tool for removal of CARB bearings from a non-split housing


5Fig

The lock nut is left on the shaft thread to provide a stop

6Fig

Removal of a small CARB toroidal roller bearing using a drift ofspecial design

36

1 Product information 2 Recommendations 3 Product dataPage................. 3 Intergrated maintenance Page ............... 37

SKF concept for cost saving

A daily occurrenceWhatever the branch of industry – un-planned stoppages are still not a thingof the past. They are not only annoying,but costly too. And with the heighteneddemands for prompt and just-in-timedeliveries they may be even moreexpensive.

The SKF answerThe bearings in a machine can belikened to the heart of a living being.When the bearing comes to a stand-still, the machine does too.

And just as a doctor will listen to theheart of a patient, so it is possible tolisten to the bearings in order to judgethe condition of the machine. It is pos-sible to determine whether the bearingis in danger of failing prematurelybecause of faulty mounting, poorlubrication or other causes.

If the importance of the bearings isneglected this will inevitably lead tohigh costs, unnecessary stoppagesand, in the worst case, to damage to

other components of the machine.However, if the bearings are given theattention they deserve, not only willproductivity be increased, but costsfor maintenance, purchasing and stor-age be reduced.

All that is needed is an IMS contractwith SKF. IMS stands for IntegratedMaintenance Solutions and consists oflinking customer and SKF resources.

This involves a multi-stage pro-gramme that includes the followingpoints:

• common problem definition and target setting,

• optimization of spares stocked,• reduction of purchasing costs,• choosing the right bearings,• caring for the bearings,• monitoring the machine condition,• having the correct tools and

lubricants on hand,• customer-specific training, and• a repair service.

Obviously it is possible to accept thewhole programme or to select onlyparts of it. Whatever the choice, it will

be a win-win situation. More informa-tion can be obtained from the nearestSKF office or authorised dealer.

Monitoring temperature Monitoring noiseSKF experts bring their experience to lubricant analysis

37

3

1 Product information 2 Recommendations 3 Product dataPage................. 3 Page............... 12 Bearing data

DesignsCARB toroidal roller bearings are available

• with a caged roller assembly (➔ fig ) and

• in a full complement version (➔ fig ).

They are produced with cylindricalbore and particularly the caged bear-ings are also produced with a taperedbore. Depending on the bearingseries, the taper is either 1:12 or 1:30.

2

1

Sealed bearingsToday, the range of sealed bearings(➔ fig ) consists of small and mediumsize full complement bearings for lowspeeds. These bearings with seals onboth sides are filled with a high tempera-ture long life grease and are mainten-ance-free.

The double lip seal suitable for hightemperature operations is sheet steelreinforced and made of hydrogenatedacrylonitrile butadiene rubber (HNBR).It seals against the inner ring raceway.The outside diameter of the seal isretained in an outer ring recess andprovides proper sealing also in appli-cations with outer ring rotation.The sealscan withstand operating temperaturesin the range of –40 and +150 °C.

The sealed bearings are filled with a premium quality, synthetic ester oilbased grease using polyurea as thick-ener. This grease has good corrosioninhibiting properties and can be usedat temperatures between –25 and+180 °C. The base oil viscosity is 440 mm2/s at 40 °C and 38 mm2/s at100 °C. The grease fill is 70 to 100 %of the free space in the bearing.

Sealed bearings with other lubricat-ing greases or degrees of greasefillcan be supplied on request.

DimensionsThe boundary dimensions of CARBtoroidal roller bearings are in accord-ance with ISO 15:1998. The dimen-sions of the adapter and withdrawalsleeves correspond to ISO 2982-1:1995.

TolerancesSKF CARB bearings are manufacturedas standard to Normal tolerances.Bearings up to and including 300 mmbore diameter are produced to higherprecision than the ISO Normal toler-ances. For example

3

• the width tolerance is considerably tighter than the ISO Normal toler-ance,

• the running accuracy is to toleranceclass P5 as standard.

For larger bearing arrangementswhere running accuracy is a key oper-ational parameter, SKF CARB bearingswith P5 running accuracy are also avail-able. These bearings are identified bythe suffix C08. Their availability shouldbe checked.

The values of the tolerances are inaccordance with ISO 492:2002.

Internal clearanceCARB toroidal roller bearings are produced as standard with Normalradial internal clearance. Many of thebearings are also available with C3clearance and some with the smallerC2 or the much larger C4 clearance.

The radial internal clearance limitsfor

• bearings with cylindrical bore aregiven in table on page 38 and for

• bearings with tapered bore in table on page 39.

They are valid for bearings beforemounting and under zero measuringload.

Axial displacement of one ring inrelation to the other will graduallyreduce the radial internal clearance ina CARB toroidal roller bearing. Withthe amount of axial displacementencountered in normal cases, there willbe little effect on the radial internalclearance.

CARB toroidal roller bearings areoften used together with sphericalroller bearings and their internal clear-ance has been selected with this inmind. The clearance is larger than fora comparable size of spherical rollerbearing having the same clearance

2

1

Bearing data – general

1Fig

2Fig

3Fig

Caged CARBtoroidal rollerbearing

Full complementCARB toroidalroller bearing

Sealed CARBtoroidal rollerbearing

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1 Product information 2 Recommendations 3 Product dataPage................. 3 Page............... 12 Bearing data

Bore Radial internal clearance diameter C2 Normal C3 C4 C5dover incl. min max

CARB toroidal roller bearings – a revolutionary...

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